My hard drives shut down for no reason and on their own

OK guys, here's the deal. I've been having this issue for a while now, and it occurs every couple of months. I have an SSD for my Windows 7 sistem, and 2 hard drives. And the problem happened again today. Suddenly I notice something weird, for example my Skype logs out and say it has an I/O problem (my cache folder is on my hard drive). So I go to My computer and I see that all my partitions that reside on that hard drive are gone. So I have to reset my PC to temporarely resolve the issue. But after an hour or so it happens again. If I shut down my PC I will get more time, but only few hours. So I have to open my case and disconnect that drive and reconnect it to a different Sata port. And that solves it. For a month or two. After couple of months it happens again. I've check all my hard drives with HD tune, no issues. I tried new sata cables, 5-6 of them, and that didn't help. I happened with both of my drives. In every sata slot. Any ideas?

At BIOS settings under power settings, is there some option to shutdown HDD?

Go to Control Panel\All Control Panel Items\Power Options - Change plan settings - Change advanced power settings - HDD.

Go to Control Panel\All Control Panel Items\Power Options - Change plan settings - Change advanced power settings - HDD.

This is set to NEVER.

But everything about a setting is a moo point, because the moment I switch the sata port, everything is fine for the next couple of months. So if the a setting is the problem, it would happen again on a different sata port.